Syringes used for delivery of medicaments are principally constructed of a barrel and a stopper. The stopper is slidably fitted within the syringe barrel and may have a plunger rod affixed to it for actuation of the syringe and delivery of medicament. The stopper is generally constructed of an elastomer, with silicone oil applied. The silicone oil is applied to reduce sliding friction between the stopper and barrel and to improve the seal between them. The oil, allows for ease of sliding when administering a dose which ensures the full dose can be administered. This is particularly critical in the case of pens and so-called auto injecting syringes. The oil is also critical to prevent jamming of the device which can lead to trauma at the site of injection.
Though silicone oil has traditionally been utilized in syringes, such use can be problematic. In pharmaceutical applications, the use of silicone oil is particularly concerning. For example, the silicone oil may undesirably degrade medicine contained in the syringe and may cause aggregation of certain proteins in the medicines.
One concern for both lubricated and non-lubricated syringes is that of an effective seal between the stopper and the syringe barrel. Lack of an effective seal can lead to reduced shelf life and/or contamination, for example. Accurate methods of determining effective seals either prior to, or following filling of a syringe (a “pre-filled” syringe) remain to be realized.